Blade tracking and guiding mechanism for band saw construction



Aug. 8, 1961 J. w. EDGEMOND, JR., ET AL BLADE TRACKING AND GUIDINGMECHANISM FOR BAND sAw CONSTRUCTION Criginal Filed Feb. 13. 1956 6Sheets-Sheet 1 INVENTORS John W Edge/7107i]: By Vl ////am C. GrageanAug. 8, 1961 .1. w. EDGEMOND, JR., ETAL 2,995,160

BLADE TRACKING AND GUIDING MECHANISM FOR BAND SAW CONSTRUCTION OriginalFiled Feb. 15, 1956 s Sheets-Sheet z FIE-5:...

BY \w- ATTORNEYS Aug. 8, 1961 J. W. EDGEMOND, JR., ETAL BLADE TRACKINGAND GUIDING MECHANISM FOR BAND SAW CONSTRUCTION Original Filed Feb. 1:5,1956 6 Sheets-Sheet 4 IN V EN TOR. Jo/m [Midge/770x70, .01

ATTORNEYS 1951 J. w. EDGEMOND, JR., ETAL 2,995,160

BLADE TRACKING AND GUIDING MECHANISM FOR BAND SAW CONSTRUCTION 6Sheets-Sheet 5 Original Filed. Feb. 13, 1956 y NQ QQ as INVENTORS John Wfdgemonoj/r ATTOPA/EYJ' Original Filed Feb. 13, 1956 Aug. 8, 1961 J. w.EDGEMOND, JR., ETAL 2,995,160

BLADE TRACKING AND GUIDING MECHANISM FOR BAND SAW CONSTRUCTION 6Sheets-Sheet 6 F'IE J 'L PlE lE I r 73.9 T T 56 58 f1 1 2A fig 65 Cl 7/52 f p 59 ;4\ f f 67 f9 J Jl IN V EN TOR) John W [dye/7700 0, Jr: ByW/'///am C Grog ear;

$ M AM'M ATTORNE YJ 2,995,160 BLADE TRACKING GUIDING MECHANISM FOR BANDSAW CONSTRUCTION John W. Edgernond, '.lr., Los Altos, and William C.Grosjean, Mountain View, Calif., assignors, by mesne assignments, toYuba Consolidated Industries, Inc., San Francisco, Calif., a corporationof Delaware Original application Feb. 13, 1956, Ser. No. 565,054, newPatent No. 2,903,027, dated Sept. 8, 1959. Divided and this applicationJan. 28, 1959, Ser. No. 792,941

2 Claims. (Cl. 143-27) This invention relates to band saws.

Band saws are well known and consist of an endless blade which passesover two or more pulleys which drive it past a working station. When thesaw blade in a conventional band saw is tracking properly over thedriving and idler pulleys, it does not engage the backup rollers, butwhen a work piece is brought into engagement with the blade, the bladeis urged into engagement with the back-up rollers. Thus, when the loadagainst the blade is the heaviest, it is normally urged out of its idealand most eflicient path. Moreover, when the work is drawn away, theblade also tends to be drawn away from its most effective path, and,since there are no back-up rollers on the toothed side of the blade, itmay not only be urged from the ideal operating path but may be removedfrom the guides because the forces tending to retain the blade in itspath are at their when the blade is properly adjusted to operate in itsproper path at the crowns of the pulleys. The forces tending to retainor restore the blade to its path increase as the blade is urged from thecrowns to one side or the other of the pulley or pulleys.

We have found that conventional band saws require and provide fouradjustments and it is an object of our invention to provide a band sawconstruction in which the number of adjustments is reduced.

Conventional band saws required an adjustment or relocation of theback-up rollers when blades of ditferent widths are used. For example,when the blade of a conventional band saw is properly adjusted it willride the crowns of the pulleys, and the back-up rollers must beadjustable so they may be positioned immediately adjacent the blade toretain the blade in the path thus defined when a work piece is urgedagainst it.

It is an object of this invention to provide a band saw construction inwhich the back-up rollers need not be adjusted as blades of difierentwidths are used and in which a factory setting or other permanentsetting may be retained regardless of blade width.

I-t is a further object of this invention to provide a band sawconstruction in which the backup rollers define the path in which theblade operates and in which the blade is urged into and caused tooperate in that path.

It is a further object of this invention to provide a band sawconstruction in which the backup rollers define the path in which theblade is to operate and in which the blade is urged into that path bythe construction and mounting of the pulleys.

Conventional band saws require a means for adjusting at least one of thepulleys to provide proper blade tension. This is normally accomplishedby mounting the pulley in a block or blocks which are movable in guideswhereby the pulley centers may be spaced further apart or nearertogether.

' It is an object of this invention to provide a band saw constructionin which one of the pulleys is mounted upon a crank arm assembly whichis pivotally mounted upon the frame to provide a simpler and more ruggedframe construction.

Conventional band saws require means for tilting the axis of one of thepulleys to cause the blade to track on rates arm s a "s ice band saw, hebacks off on all adjustments. Then he first mounts the blade on thepulleys. He next adjusts the pulleys for proper tension for the blade.He may then turn the blade by hand and observe the path which the bladefollows. By adjusting the tilt mechanism which varies the tilt of theupper pulley, he causes the blade to seek the crowns of the pulleys andits proper path. He next adjusts the back-up rollers and finally theguides are adjusted. Thus it is apparent that such a constructionrequires that all our adjustments be made or at least reexamined andreconsidered when a new blade is' mounted upon the saw.

It is an object of this invention to provide a band saw construction inwhich the correct tilt of the axis of rota-- tion or of the plane ofrotation of the pulley is automatically obtained.

It is a further object of this invention to provide a device in whichthe pulley may be tilted without requiring readjustment or relocation ofthe backup rollers.

It is a further object of this invention to provide a band sawconstruction in which only two of the normal adjustments, bladetensioning and guide shoe adjustment, are required with a change ofblade and in which the back-up rollers need not be relocated and inwhich the pulley is automatically tilted when a blade is changed.

This application is a division of application Serial No. 565,054, filedFebruary 13, 1956, now Patent No. 2,903,027.

Other objects and advantages of our invention will appear from thefollowing specification taken in conjunction with the accompanyingdrawings in which:

FIGURE 1 is a front elevational view of a band saw incorporating ourinvention and showing the same mounted on one end of a Combination PowerTool of the type disclosed in Edgernond et a1. application Serial No.494,468, filed March 15, 1955, (now Patent 2,927,612, granted March 8,1960);

FIGURE 2 is a cross sectional view of the band saw illustrated in FIGURE1, showing the two pulleys over which the saw blade is operated andshowing the means for raising and lowering the upper pulley and fortilting the table;

FIGURE 3 is a View taken through the line 33 of FIGURE 2 showing themounting of the lower pulley and the table and the tilting of the upperpulley;

FIGURE 4 is a view taken along the line 44 of FIG- URE 2 and shows apart of the table mounting mechanism and the guide shoe mechanism;

FIGURE 5 is a view taken along the line 5--5 of FIG- URE 2 and shows thetorsion arm mounting of the upper pulley and the single controlmechanism which permits one hand operation of the upper guide;

FIGURE 6 is a view taken along the line 6-6 of FIG- URE 2 and shows theupper back-up roller and its mount- FIGURE 7 is a view taken through theline 77 of FIGURE 2 and illustrates the apparatus for raising andlowering the upper pulley and for adjusting the blade tension;

FIGURE 8 is an enlarged detailed view of the guide shoe mechanism infully retracted position, the means for adjusting the same and the lowerback-up roller;

FIGURE 9 is a side view of the mechanism illustrated in FIGURE 8;

FIGURE 10 is a detail taken along the line 1010 of FIGURE 8 showing thesingle lever control operating Patented Aug. 8, 1961 mechanism forraising and lowering the upper guide shoes and for locking the same in apredetermined selected position. The third guide roller which isimmediately above the work and which is normally not engaged by theblade, except when a work piece is being cut, is also shown in thisfigure.

FIGURE 11 is a schematic view of our band saw showing the degree of tiltof the axis of the upper pulley and the conical shape of the pulleys;

FIGURE 12. is a schematic view of a conventional band saw utilizingcrowned pulleys;

FIGURE 13 is a schematic view of another type of band saw showing theutilization of tapered or conical pulleys on parallel axes;

FIGURE 14 illustrates a modified type of band saw showing square pulleysmounted on non-parallel axes; and

FIGURE 15 is a schematic view of tapered pulleys on a four pulleymachine on non-parallel axes.

As indicated in the drawings, our device is adapted to be mounted uponone end of the Combination Power Tool disclosed in the Edgemond et a1.Patent No. 2,927,- 612. While this tool illustrates a preferredembodiment and mounting, it must be understood that our device may bemounted for separate operation on a stand of its own and may be drivenby an independent motor.

As is pointed out in the above identified Edgemond et al. patent, thecombination power tool includes a pair of opposed identical tool benchends and 11 which support castings 12 and 13. The castings 12 and 13accommodate parallel longitudinally extending tubes 14 and 15. Tubes 15are supported at one end by casting 13 and at their other ends bycasting 12a which may be clamped to casting 12' thereby providing asturdy, rigid bench or supporting member.

The end casting 12 is provided with a pair of parallel spaced verticalsockets which are adapted to receive a pair of spaced parallel mountingtubes 16 and 17 whose other ends are received in similar recesses in amember 18 which forms a mounting base for our band saw.

The parallel tubular ways 15 provide a mounting for a headstock memberindicated generally at 19 which supports an electric motor which isoperatively connected to the power take-ofi shafts 21, 22 and 23, eachof whose functions has been previously described in the aforemen tionedEdgemond et al. application. We provide a drive shaft 24 which isadapted to be coaxially aligned with the power take-oft shaft 23 and tobe operatively connected thereto by means of a readily removablecoupling 26. It is apparent that our device can be mounted in anysuitable base which is provided with spaced parallel cylindricallyshaped sockets which are adapted to accommodate the mounting tubes 16and 17 and which is further provided with a motor and means foroperatively connecting the same to the driven shaft 24.

Generally speaking, our band saw is supported on the base member 18which, as shown in the drawings, consists of a C-shaped casting whichforms the framework for our entire structure. The lower arm 18a of the Cshaped casting 18 provides a mounting for the shaft 24 and the pulleywhich drives the saw blade. This portion of the base also provides amounting. for the table which supports the work piece. The narrowportion 18b of the member 18 serves to support the upper portion 18c andprovides a throat area immediately above the table within which the workpiece may be positioned, and the upper portion 18s provides a supportfor the idler pulley over which the saw band is driven, all as will morefully hereinafter be described.

The member 18 is preferably in the form of a die casting and appropriatestrengthening ribs, bosses, etc. are molded integrally therewith.

The driven shaft 24 is rotatably mounted in a bearing 27 which in turn.is mounted in an appropriately positioned and machined boss 28 castintegrally with the base 18. The shaft 24 supports a driving pulley 29whose 4 rim 31 is grooved at 32 to accommodate an annular tire 33 whichmay be formed of rubber, either natural or synthetic, or some otherresilient material which will not dull the saw teeth and which will notbe seriously cut by the saw teeth. The shaft 24 is coaxial with thedriving shaft 23, and the plane of rotation of the pulley 29 isvertical. The upper pulley 34 is rotatably mounted upon an axle 36 whichis supported upon a torsion arm 37 which is pivotally mounted upon ashaft 38. Torsion arm 37 is provided with a leaf spring 39 which extendsdownwardly, as indicated in FIGURE 2. The lower end of the spring 39 isformed, as shown in FIGURE 8, with a recessed portion 41 which isadapted to partially surround a bolt 42. The bolt 42 is provided withnonthreaded portions 42a and 42b and is rotatably mounted in a U-shapedmember 43 which is secured to bosses formed on the base 18. Intermediatethe parallel arms or ends 43a and 43b of the U-shaped member 43 andthreadedly mounted upon the bolt 42 is a nut 44 which is provided with aflat surface 46 which engages a similar surface 47 on the base of theU-shaped member 43. As the bolt 42 is turned, the member 44 will beurged in one direction or another, depending upon the direction ofrotation of the member '42. The weight of the pulley 34, axle. 36,torsion arm 37, and the resistance of the saw blade 45 will tend to urgethe pulley 34 downwardly and the lower end of the spring 39 to the left,as viewed in FIGURE 2, against the member 44. When the member 44 isurged to the right, as viewed in FIGURE 2, the pulley 34 will be raisedupwardly about the axis of the shaft 38. The pulley 34 is provided witha groove 48 and tire 49 which are substantially identical to the groove32 and tire 33 on pulley 29.

A pair of rollers 51 and 52 are suitably mounted immediately adjacentthe entering sides of the pulleys 29 and '34. It must be borne in mindthat the pulleys 29 and 34 are rotating in a clockwise direction whenviewed in FIGURE 2, and therefore the roller 51 is mounted in such amanner that the blade 45 engages it just before it engages the pulley34. The roller 52 is mounted in such a manner that the blade 45 engagesit just before it engages the pulley 29. Both the rollers 51 and 52 arepermanently positioned with respect to the frame 18 to engage the backor non-toothed edge of the blade 45 to define the predetermined path ofthe blade 45 and to resist or overcome the tendency of the blade to moveto the right, as viewed in FIGURE 3.

As has been previously pointed out, the drive shaft 24 is horizontal.The axis of the axle 36 is set at an angle of one degree and fifteenminutes to the horizontal however, as shown in the schematic sketch,FIGURE 11. The pulleys 29 and 34 are conical in that a plane tangent tothe periphery would be an angle of approximately two degrees to the axisof rotation, as likewise shown in FIGURE 11.

Therefore, the angle of the blade 45 with respect to the axis ofrotation of the pulley 29 is less 37% minutes. The angle of the bladewith respect to the axis of the axle 36 is likewise 90 less 37 /2minutes, all as illustrated in FIGURE 15. It will be apparent that theaxes of the axle 36 and the shaft 24 could be offset 37 /2 minutes withrespect to the horizontal, and the blade could be driven in a verticalplane, but since the driveshaft 24 must be horizontal, it is necessary,in efiect, to tilt the whole device so that the blade does not operatein a vertical plane but operates in a plane which is 37%. minutes offthe vertical.

A suitable scale 53 is secured to the torsion arm 37 and rotates aboutthe shaft 38 generally as shown in FIGURE 2 in such a manner that oneedge of the spring 39 is adapted to be aligned with a specific indiciumupon the scale. The indieia on the scale 53 reflect different widths ofsaw blades 45 and show the recommended factory setting for theadjustable pulley 34 for blades of difierent widths. Blades of differentWidths operate at different tensions; the greater the width of the bladethe greater the tension while the narrower the blade, the less thetension. Thus when a new blade is mounted on our device the wholeassembly consisting of the pulley 34, arm 37 and scale 53 are rotatedabout the member 38 until all of the slack is taken out of the blade.Then by further movement of the member 44, the spring 39 is bent or putunder tension until its edge lines up with the appropriate indicium onthe scale 53. However when tension upon spring 39 is increased toincrease the blade tension for a heavier or thicker blade, the pressureof the blade 45 against the back-up roller 51 is increased. Tocompensate for this increased pressure against the back-up roller 51,the torsion member 3-7 twists (due to increased blade tension) and thusautomatically relocates the tilt axis of the shaft 36 and pulley 34.This reduces the conical effect of the pulley 34 and the lead-in effectwhich the tilted conical pulley 34 normally has on the blade 45 and,further, reduces the angle of the back edge of the blade 45 to the axisof pulley 34 thereby decreasing the pressure of the blade 45 on theback-up roller 51. When a lighter blade is used the pressure upon thespring 39 is decreased, the: tension on the blade 45 will be lessenedand the pressure-on the back-up roller 51 will be decreased. The tensionof a narrower or lighter blade will twist the member 37 to a lesserextent, will result in a lesser reduction of the: conical effect of thepulley 34 and a lesser reductionof the lead-in efiect of the blade 45,and will increase the angle of the back edge of the blade '45 to theaxis of pulley 34.

While we have shown a torsion arm 37 we contemplate that the same resultwould occur if the pulley 34 was supported by a rigid member having atorsion mountmg.

Operation of our tensioning means and our automatic tilting and trackingmechanism may briefly be described as follows:

Let it be assumed that the device is in the condition illustrated in thedrawings. A blade 45 of selected width is positioned about the pulleys29 and 34. The width of the blade is noted and the arm 39 is positionedwith respect to the scale 53 so that it is aligned with the indiciumwhich corresponds to the width of the blade. The back-up rollers 51 and52 are inspected to determine that they define a plane or path ofoperation of the blade 45 which has been designed to be at an angle of37% minutes off the vertical.

The cover may be replaced so that the pulleys 29 and 34 and the greaterlength of the blade 45 is shrouded.

The shaft 24 is connected through a coupling 26 to the driving shaft 23.The motor may be started.

The blade 45 will be driven past the work station and because of thetilt of the pulley 34 and the generally conical shape of the pulleys 29and 34, the blade 45 will seek the crown or greatest diameter of thepulleys 29 and 34 and will be urged to the right as viewed in FIGURES 3and 11 into engagement with the back-up rollers 51 and 52. These rollersare positioned at points where they engage the blade immediately beforeit engages the associated pulley. Thus, the back-up rollers define thepath of the blade. The mounting of the pulleys and their conical shapekeeps the blade in that path.

As has been previously mentioned, when a Wider blade is used, greatertension is required and the tension of the blade is adjusted byincreasing the tension of spring 39. The greater tension of a widerblade would increase the blade pressure against the back-up roller 51and to prevent excessive pressure and resultant excessive wear we havemounted the pulley 34 upon a torsion member 37. Thus the increasedtension of a wider blade twists the member 37 about its longitudinalaxis and changes the tilt of the axle 36 and of the plane of the pulley34. This results in a lessening of the lead-in effect which the coni- 6cal pulley 34 normally has on the blade 45 and decreases the pressure ofthe blade upon the back-up roller 51. A

When a blade is operated over a pair of crowned pulleys" 56 and 57rotating in the same plane and about parallel axes 58 and 59, the sawblade will seek the crowns, will tend to follow the path indicated at 60(see FIGURE 12 and will seek a path in the plane of the greatestcircumferences of the pulleys 56 and 57.

We have found that when conically shaped pulleys of the type illustratedin FIGURE 13 at 61 and 62 are r0 tated about the axes of parallel shafts63 and 64, the blade 65 will seek the plane of the greatestcircumference of each of said pulleys 61 and 62 and will, unlessprevented by annular flanges on the pulleys 61 and 62 or by rollers ofthe type 51 and 52 on our device, continue to move to the right, asviewed in FIGURE 13, and will ultimately become entirely disengaged fromthe pulleys 61 and 62.

We have also found that when pulleys 66 and 67, as shown in FIGURE 14,are mounted for rotation about offset axes 68 and 69, the samephenomenon will occur. Let it be assumed that the axes 68 and 69 areoffset one degree and fifteen minutes, as has previously been describedin connection with our preferred embodiment. Let it also be assumed thatthe rims of the pulleys 66 and 67 are not crowned or tapered. We havefound that the blade 70 travels in a plane at an angle with respect toeach axis and that rollers 71 and 72 are required. It would ordinarilybe assumedthat the blade 70 would travel upwardly or to the left, asviewed in FIGURE 18, but it must be borne in mind that the blade 70engages pulley 66 at a point 73 and the tracking or frictionalengagement of the blade with the pulley 66 keeps the blade from climbingto the left, and, in fact, urges it to the right, necessitating theutilization of rollers 71 and 72. In other words, the point 73 at whichthe blade 70 engages the pulleys 66, will, as the pulley 66 rotates,approach the point 73a and, in this manner, the saw blade will becontinually urged to the right, as viewed in FIG- URE 14.

We have also noted a phenomenon, as illustrated in FIGURE 15, in which aplurality (more than two) of tapered pulleys (of the type shown inFIGURES 12 and 14), 76, 77, 78 and 79 rotate about offset axes. Theblade 80 will tend to operate in the plane defined by the greatesteffective circumference of the combined pulleys 76, 77, 78 and 79,previously described, and back-up rollers would be required to engagethe non-toothed or smooth surface of the blade 80 to maintain the sameupon the pulleys 76 to 79 inclusive.

The table which is adapted to support the work piece consists generallyof a flat member 101 which is tiltably supported as viewed in FIGURE 2.The base 18 is provided with a pair of bosses 102 and 103 (FIGURES 3 and4) each of which accommodates a bolt 104 and 105. A pair of identical'arcuately shaped members 106 are secured to the bottom side of thetable 101. The members 106 are provided with arcuate slots 107 throughwhich the bolts 104 and 105 pass, as viewed in FIGURES 3 and 4, and thebolts 104 and 105 define the path of the arcuate slots 107. The arcuatemembers 106 and their arcuate slots 107 are so designed that theircenters coincide at 108 (which defines a line across the middle of thetable 101) so that the table 101 pivots about the line 108. The line 108also determines the center line through which the blade 45 passes sothat the table 101 may also be said to pivot about the center line ofthe blade 45.

Substantially continuous tension is maintained upon the members 106 bythe nut and bolt assembly 104, but a locking action is obtained throughthe handle 105111 on the bolt 105. When the handle 1050 is tightened,the head of the bolt 105 and the washer 105b frictionally engage themembers 106 and urge the same into greater frictional engagement withthe boss 103 on the frame 18, thereby preventing the movement of themembers 106,

When h ha 105a leased, the mem er 0 may be swung about the center line108, with the result that the table 101 may also be tilted about the,axis defined by the center line 108.

We claim:

1. In a band saw construction, a frame, a lower pulley rotatably mountedon said frame, an upper pulley, a saw blade carried by said pulleys, agenerally horizontally disposed arm pivotally mounted on said frameadjacent one end of said arm, means for rotatably mounting said upperpulley on that end of said horizontally disposed arm remote from itspivotal connection to the frame, a generally downwardly disposed scaleplate mounted on said arm adjacent its pivotal connection to the frame,indicium on said scale plate, a leaf spring secured to said arm adjacentits pivotal connection to the frame adapted to flex in a plane parallelto the plane of said scale plate and normal to the axis of said pivotalconnection and to co: op ate with s n um to o m a au e means f adjustingthe tension on said saw blade comprising adjusting means on said frameengaging said leaf spring at a point adjacent its free end to move'thesame about the pivotal connection to alter the position of said arm andupper pulley with respect to said lower pulley and of said leaf springwith respect to the indioium on said scale plate.

2. In a band saw construction, a frame, a lower pulley rotatably mountedon said frame, an upper plll j y, a saw blade carried by said pulleys, agenerally horizontally disno ed a m pivqtally mou ted 9 sai tr ms adi wea end i sa m, m ans fo re ata l moun said up- Pe Pulley on ha a d ofsai ho izontal d s e ar m e m i p a onnection is he am h a e of rotationof said pulleys and the, of said pivotal connection being parallel, agenerally downwardly disposed scale plate mounted on said arm adjacentits pivotal connection to the frame, indicinrn gn said scale plate, aleaf spring secured to said arm adjacent its pivotal connection to theframe adapted to flex in a plane parallel to the plane of said scaleplate and normal to the axis of said pivotal connection and to cooperatewith said indicium to form a gauge, means for adjusting the tension onsaid saw blade comprising adjusting means on said frame engaging saidleaf spring at a point adjacent its free end to move the same about thepivotal connection to alter the position off said arm and upper pulleywith respect to said lower pulley and of said'leaf spring with respectto the indicium on said scale plate.

References Cited in the tile of this patent UNITED STATES PATENTS801,815 Seymour Oct. H), 1905 1,323,818 Berry Dec. 2, 1919 1,879,145Erickson Sept. 27, 1932 2,31l,762 Kottmann et a1. Feb. 23, 19432,806,490 Kennedy Sept. 17, 1957 2,903,027 Edgemond, et a1. n Sept. 8,1959

